Sure I have but that's mostly a problem for terminal C in my experience, as the budget airlines fly from there and they seems to have a different ratio of personnel to passengers. Airlines that mostly serve business travelers usually have better gate positions and more staff.

It's not personnel, they have to stop the queues from moving through security in order to prevent over crowding in the gate rooms which, are always over packed full of people.

Berlin's awful setup results in delays across the region, it's no wonder other airports are reluctant to link there and divert to Frankfurt instead.

You must be mixing up the airports. Tegel is unique in that it has security and passport controls for each individual gate.

This allows you to arrive at almost the exact moment the gate closes because there will be no passengers for other flights in a queue with you. The gate agents can even see you going through security and will wait for a minute or so.

This is true except for Terminal C, which is indeed a mess.

I still like Tegel a lot, as it's very close to the West center of the city.

Indeed, Terminal C vs. A is a big difference.

My worst airport experience has been trying (and failing, twice; on consecutive days) to fly from Tegel Terminal C to Helsinki (EasyJet). My best airport experiences have been flying from Tegel Terminal A (Finnair) to Helsinki.

if you happen to arrive at tegel ahead of time or even worse your flight is delayed, you are screwed. Once in the security area there is little to no decent food nor shopping option.

And yet it's still better than JFK.

Singapore's airport also does right-before-gate screenings at 3 of its 4 terminals.

Unlike Tegel, though, the gate area and the screening areas are open spaces, with glass to separate. Tegel always feels a bit claustrophobic, and as a jet-lagged traveller my first time departing, I admit it took awhile for me to figure out where the hell I needed to go.

source: https://www.changiairport.com/en/airport-guide/departing/sec...

Unless a plane is delayed or cancelled at the last minute, which in TXL's case is frequent. This results in a gate full of too many people and a slow down moving anyone anywhere.